params = {
    'fromPeer': 'Tom',
    'content': '{"_lctext":"games","_lctype":-1}',
    'convId': '5789a33a1b8694ad267d8040',
    'toPeers': ['Jerry'],
    '__sign': '1472200796787,a0e99be208c6bce92d516c10ff3f598de8f650b9'
}
print (params)
if ('fromPeer' in params.keys()):
    print("yes")
else:
    print("NO")